1. The Field of the Invention
The present invention relates to transmitting electronic messages between enterprises. In particular, the present invention relates to communicating messages from a sender outside of the recipient""s network to a bridgehead server inside the recipient""s network, where the address of a messaging server associated with the recipient is resolved.
2. The Prior State of the Art
Communication over the Internet takes on several forms, principally e-mail, chat, video and audio. These forms of communication are used in a variety of different contexts. Email is generally not perceived as xe2x80x9creal-timexe2x80x9d or xe2x80x9cimmediatexe2x80x9d; messages may be read hours or days after they are sent. Chat is principally used as a social medium or for information sharing, not for point-to-point communication. Video and audio are both real-time, but they are both relatively difficult to use, and widespread acceptance requires improvements in existing technology and user interfaces.
Another form of communication that exists on the Internet to a limited extent is instant messaging. For instance, a sending user can send a message to a recipient user, thereby causing the message to almost immediately appear on the computer terminal used by the recipient. The prototypical instant messaging system is the Zephyr system, which has been used on Athena, the campus computer network of the Massachusetts Institute of Technology in Cambridge, Mass. Zephyr permits any Athena user to send popup messages to any other Athena user, but not to any user across the Internet.
Instant messaging differs from chat communication in several respects. First, chat users typically focus their attention on a chat window for the duration of communication while instant messaging users are generally alerted on a per-message basis, allowing them to pay attention to instant messaging only when attention is required. Additionally, the chat model only makes sense for human-to-human communication, while instant messages may be used to transmit notifications from any source, such as a human user, an automated system that send notifications to remote sites, and the like.
Firewalls are machines commonly used for enforcing corporate network security policies; most business users connect to the Internet through a firewall. Firewalls represent a significant impediment to real-time communication between Internet users. Firewall designs generally prohibit external entities on the Internet from directly connecting to internal entities protected by the firewall. While such security mechanisms prevent external entities from maliciously manipulating internal entities, they have had the side effect of preventing asynchronous communication to an internal entity. Existing protocols for real-time Internet messaging are generally incapable of working through a firewall without explicit firewall policy modifications by systems administrators.
As network systems administered by corporate entities and other organizations have grown larger and more widespread, the use of firewalls and related security techniques has increased during recent years. As data transmission rates have increased, the ability to send large amounts of data over the Internet between local area networks has also increased. The fill potential of Internet communication has not been realized, however, because of the inability to securely operate instant messaging systems through firewalls.
The present invention relates to messaging systems that are compatible with firewalls, thereby permitting instant messages to be transmitted over the Internet. According to the invention, a sending client residing at a network administered by a first organization can cause an instant message to appear at a recipient client machine at another network administered by a second organization, even though either (or both) of the organizations may use a firewall to protect its network.
Each network has a hierarchical arrangements of components, including a firewall, one or more bridgehead servers exposed through the firewall, one or more messaging servers each being capable of receiving messages from one or from more than one of the bridgehead servers, and one or more clients assigned to each of the messaging servers. Incoming messages include the address of the bridgehead server and information identifying the recipient client, but do not include the address of the messaging server associated with the recipient client.
Incoming messages are transmitted through the firewall and are received by the bridgehead server to which they are addressed. The bridgehead server resolves the address of the messaging server to which the recipient client is assigned. For instance, the bridgehead server compares the information identifying the recipient client with directory information stored at the network. The directory information can include a database of clients of the network and the messaging server to which each client is assigned. Once the address of the appropriate messaging server is resolved, the message is transmitted to that messaging server and, in turn, to the recipient client.
An outgoing message can bypass any messaging server and bridgehead server associated with the client that sends the message as it is sent across the firewall and to the recipient""s bridgehead server. Transmitting outgoing messages in this manner decreases the number of transmission hops that would otherwise be needed if the outgoing message were to pass through the messaging server and the bridgehead server.
The message transmitted in the foregoing manner arrives at recipient client without the sending client knowing the identity or the address of the messaging server associated with the recipient client. Moreover, the sending client does not access the messaging server directly, but instead sends the message to the bridgehead server. The organization in which the recipient client resides can protect its network using a firewall to prevent direct outside access to its messaging servers, while allowing instant or other real-time or rapid messaging systems to operate on its network. These features of the invention provide a desirable degree of security that has not previously been possible in connection with instant messaging. Accordingly, the invention allows real-time messaging to be used in many organizations where it would otherwise not be used without compromising organizational security. The invention also is scalable to substantially any number of users.
A recipient of a message can generate and transmit a response to the message as quickly as desired. Transmission of a response message is similar to that of the original message, with the original recipient client sending the response and the original sending client receiving the response. The client that sends the response (i.e., the original recipient client) does not need to know the address of the messaging server associated with the client that receives the response (i.e., the original sending client). In this manner, two or more clients located remotely with respect to one another can rapidly communicate through firewalls.
Optionally, the invention includes a system for allowing clients to track property changes (such as online status changes) of other clients designated as correspondents. When using the invention to track online status changes of other clients, each client can maintain and display a continuously updated contact list showing the online status of each selected correspondent, thereby allowing the client to know which correspondents are available to engage in real-time communication over the Internet.
The contact list feature of the invention can be implemented by maintaining at the messaging server a subscriber list for a client associated with the messaging server and a given property of that client. The subscriber list includes, for example, entries indicating which of the other clients have designated its client as a correspondent or, in other words, have subscribed to the online status property of its client. When the client logs on to its messaging server, the online status property of the client is modified. The messaging server of the client then refers to the subscriber list for the online status property and notifies each of the clients included in the subscriber list that the particular client is online. Similarly, when the particular client logs off or otherwise goes off line, the messaging server notifies the clients included in the subscriber list.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other objects and features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.